Selectable input transient voltage suppressor

Abstract

An electrical system includes an input node electrically connectable to a power supply. The system includes a plurality of voltage suppressors, with at least one of the voltage suppressors electrically connected to the input node. A voltage selection switch is electrically connected to at least one of the plurality of voltage suppressors. A controller in communication with the switch may selectively operate the switch based on a nominal operating voltage at the input node.

What is claimed is: 
     
       1. An electrical system comprising:
 an input node electrically connectable to a power supply; 
 a plurality of voltage suppressors; 
 at least one of said plurality of voltage suppressors electrically connected to said input node; 
 a voltage selection switch electrically connected to at least one of said plurality of voltage suppressors; and 
 a controller having a first output connected to said voltage selection switch to selectively operate said switch based on a nominal operating voltage at said input node, 
 wherein said plurality of voltage suppressors comprise a first voltage suppressor electrically connected between said input node and a ground reference and a second voltage suppressor electrically connected between said input node and said voltage selection switch, the second voltage suppressor and the voltage selection switch being series connected between the input node and the ground reference, 
 wherein the electrical system further comprises an output node for connection to at least one load, and at least one load operation switch electrically connected between the output node and the input node for selectively electrifying said at least one load such that when the at least one load operation switch is closed, said at least one load is connected to the input node, and when the at least one load operation switch is opened, said at least one load is electrically isolated from the input node, and 
 wherein said first voltage suppressor exhibits a first clamping voltage and said second voltage suppressor exhibits a second clamping voltage less than the first clamping voltage, such that when the voltage selection switch is closed, the input node is clamped at the second clamping voltage and when the voltage selection switch is open, the input node is clamped at the first clamping voltage. 
 
     
     
       2. The system as set forth in  claim 1  further comprising a sensor electrically connected to said input node for sensing a nominal operating voltage at said input node. 
     
     
       3. The system as set forth in  claim 2  wherein said controller is in communication with said sensor for receiving the nominal operating voltage sensed by said sensor. 
     
     
       4. The system as set forth in  claim 1  wherein said controller includes a second output, said at least one load operation switch is a transistor having a first conduction terminal connected to said input node, a second conduction terminal connected to said output node, and a control terminal connected to said second output of said controller. 
     
     
       5. The system as set forth in  claim 1  wherein at least one of said plurality of voltage suppressors is a diode. 
     
     
       6. The system as set forth in  claim 1  wherein said input node is configured to receive a direct current (DC) input from the power supply. 
     
     
       7. The system as set forth in  claim 1 , wherein the second clamping voltage is at a voltage for the input node being connected to a 12 V power supply, and the first clamping voltage is a voltage for the input node being connected to a 24 V power supply. 
     
     
       8. The system as set forth in  claim 7 , wherein the second clamping voltage is 26 V and the first clamping voltage is 43 V. 
     
     
       9. The system as set forth in  claim 1 , wherein the first clamping voltage is at a voltage for the input node being connected to a first power supply, and the second clamping voltage is a voltage for the input node being connected to a second power supply, the second power supply being at a voltage that is less than a voltage of the first power supply. 
     
     
       10. The system as set forth in  claim 1 , wherein the controller is one of a microprocessor, microcontroller, and application specific integrated circuit, and the controller executes instructions stored in memory. 
     
     
       11. The system as set forth in  claim 1 , wherein said at least one load operation switch and said voltage selection switch are controlled to conduct current simultaneously during operation of the system. 
     
     
       12. The system as set forth in  claim 1 , wherein the controller activates the at least one load operation switch only after the voltage selection switch is operated by the controller. 
     
     
       13. A method of operating an electrical system, comprising: providing, to an input node of the electrical system, a power supply; providing, to the input node, voltage suppressor circuitry comprising a plurality of voltage suppressors, each voltage suppressor exhibiting a different clamping voltage; determining whether the power supply connected to the input node is a first power supply providing a first predetermined supply voltage or a second power supply providing a second predetermined supply voltage; based upon the determination, selecting a clamping voltage for the input node and for an output node of the electrical system, the selected clamping voltage being a clamping voltage exhibited by one voltage suppressor of the plurality of voltage suppressors; and after selecting a clamping voltage, selectively activating a load operation switch connected between the input node and the output node, such that activating the load operation switch connects the output node to the input node and not activating the load operation switch electrically isolates the output node from the input node, wherein the plurality of voltage suppressors comprises a first voltage suppressor connected to the input node which exhibits a first clamping voltage, and a second voltage suppressor which exhibits a second clamping voltage that is less than the first clamping voltage, and wherein selecting a clamping voltage comprises selectively activating a voltage selection switch connected between the input node and the second voltage suppressor. 
     
     
       14. The method of  claim 13 , wherein when the voltage selection switch is open, the input node is clamped at the first clamping voltage and when the voltage selection switch is closed, the input node is clamped at the second clamping voltage. 
     
     
       15. The method of  claim 13 , wherein the first and second power supplies are DC power supplies. 
     
     
       16. The method of  claim 13 , wherein the first predetermined supply voltage is a 24V DC and the second predetermined supply voltage is 12V DC. 
     
     
       17. The method of  claim 16 , wherein the first clamping voltage is 43V and the second clamping voltage is 26V.